Telephone system



Oct. 13, 1942. R. J. TILLMAN TELEPHONE SYSTEM 2 Sheets-Sheet 1 Filed June 21, 1940 I MQ QEQE.

lNl/ENTOR By R. J T ILLMAN "mwww w ATTORNEY Oct. 13, 1942. R. J. TILLMAN 2,298,519

TELEPHONE SYSTEM Filed Jun 21, 1940 2 Sheets-Sheet 2 INVENTOR R. J TlLLMAN MWWE g ATmRNE'V Patented Oct. 13, 1942 2,298,519 TELEPHONE SYSTEM Richard J. Tillman, Bell Telephone New York, N. Y., a

Brooklyn, N. Y., assignor to Laboratories, Incorporated,

corporation of New York Application Jlinef21, 1940, Serial No. 341,634

9 Claims.

This invention relates to telephone systems and particularly to systems in which connections are established by automatic switches.

The objects of the invention are to simplify the registration of telephone designations;

systems of this character.

Telephone systems that require the called line designation to be stored at the central ofiice before it is with mechanisms known as register senders for this purpose. lhe registers of these senders play the important part of receiving the dial pulses from the subscribers station and utilizing these pulses to register the a simple magnetic medium in the form of a wire corresponding to the digits. Having thus efiectively stored the several digits of the called designation, the tape is driven through an associated reproducing element at the proper time, and this element converts the magnetized areas of the tape into corresponding trains of impulses which then serve to control the selective operation of the switches. When the stored digits have been used to set the switches, the records on the tape are erased magnetically, thus preparing it for recording the next designation.

A feature of the invention is a magnetic re- Jroducing mechanism for reproducing the stored mpulses in which the magnetized tape and a set if magnetic impulse contacts are" included in the 55;

magnetic circuit. The magnetic circuit, which is formed by members of relatively high permeability has .a narrow gap through which the moving tape passes to produce flux changes therein. The magnetic spring contacts of ,a relay form another gap in the magnetic circuit. The magnetized areas in the tape produces in the mag-v the relay netic circuit a flux which flows through contact springs and attracts them into engagement with each other. The closures of these springs produce impulses which are transmitted to the switches.

records the incoming impulses and reproduces them when they are needed to operate the switches. r

These and other features of the invention will be described more fully in the following specification. t

In the drawings accompanying the specification Fig. 1 illustrates an automatic telephone system incorporating the features of this invention. This figure illustrates diagrammatically the au tomatic switches used in establishing aconnection between subscribers, and a designation recording device for controlling the switches;

Fig. 2 shows an alternative form of the recording mechanism; and

Figs. 3 and 4 show reproducing unit. 5 Referring particularly to the drawings, a calling subscribers line I00 appears in the terminal bank of a line-finder switchF which is joined by a link circuit to a first selector switch S. The selector switch S has access through a suitable number of succeeding switches, such as selector Sl and connector C, to called subscribers lines, including the line Ifil. The link interconnecting the finder F, and selector S is provided with a senderselector switch S2 having access to common recording senders, one of which is shown. I Each of these sendersincludes a magnetic re cording mechanism I60 alternative forms of the comprising a movable magnetic wire or tape I02 which is driven by a motor "33 through a recording elementJ-M to record the dial impulses transmitted over the calling subscribers line to the recording mechanism. These impulses are delivered to the recording element I04 by means of impulse receiving relays, and the motor N13 is clutched to the shaft I20 for driving the tape l-UZ during the recording period under the control of a circuit closed through the contacts of a' sequence switch S 3. After the digits have been recorded on the magnetic tape I02, the tape is driven through an air-gap of a reproducing device comprising a relay I05 having magnetic contacts arranged in a second air-gap. The magnetic circuit including these two air-gaps is formed by the magnetic members I06 and I01. The relay I05 repeatedly closes its contacts in response to the movement of the tape through the air-gap and transmits impulses over a circuit extending through the contacts of the sequence switch S--3. These impulses serve to cause the selective operation of the switches S, S-I and C to extend the desired connection to the subscribers line IOI. Thereafter the tape I02 is driven through erasing devices I08 and IE2 to remove the magnetization and restore the tape to its neutral condition ready for the next use.

The alternate recording sender disclosed in Fig. 2 is similar to the one shown in Fig. 1 in that it utilizes the magnetic recording medium for recording the designation impulses transmitted from the calling subscribers station. It diifers, however, in that a separate recording tape or wire is provided for each of the successive digits involved in the designation. Assuming the designations have four digital places, there are provided a corresponding number of recorders 200, 20I, 202 and 203 for recording these digits. The incoming impulse series from the subscribers line are directed successively to the recorders 200, 20I, 202, 203 by a sequence switch S-4. After the digits have all been recorded the outgoing impulse circuit is associated with the successive recorders by means of a second controlling sequence switch 6-5. After all digits have been transmitted from the recorders the magnetized tapes are demagnetized by running them through erasing devices.

For the purpose of the present disclosure it is assumed that the switches F, S, S-I and C are of the step-by-step type, the selectors S and S-I and the connector C being operated by impulses transmitted directly to the operating magnets of these switches from the sender. It should be understood, however, that the invention is not limited to the use of step-by-step switches; instead it may be applied to systems in which any type of switch is used, such as the panel switch or the cross-bar switch or the relay switch. Also it has been assumed that the magnetic recording medium is a tape or wire commonly used for the purpose of recording signals magnetically. It will be obvious, however, that any form of magnetic medium, including magnetic discs or cylinders, may be used in the present system. Furthermore, it will be understood that the recording mechanism or sender is equipped with all the necessary relays and devices for performing the numerous functions usually required in the establishment of telephone connections.

For a better understanding of the invention a description will now be given of the manner in which the system operates, referring first to Fig. 1. Assume for this purpose that the subscriber of line I00 wishes to converse with the subscriber of line IOI. When the calling subscriber initiates the call, the line finder F operates and seizes the line I00, and the sender selector S-2 operates at the same time to associate the line-finder-selector link with an idle recording sender. An impulse circuit may now be traced from battery through the winding of relay I00, conductor IIO, brush III of switch S-2 thence over the front contact of the operated relay H2 in the link,

through a brush of the line finder F over the loop of the calling line and returning through the line finder and over the front contact of relay II2, brush II3, conductor II4 through the reactance coil II5 to ground. Relay I09 operates and closes an obvious circuit for slow-release relay II6. Relay IIS closes a circuit from ground through resistance I53, armature and contact of relay 0, brush II'I of selector 8-3, in position I, conductor H8 through the winding of clutch magnet II9 to battery and ground. The magnet H9 clutches the shaft of motor I03 to the drive shaft I20, and the tape I02 is driven in the direction indicated by the arrow. The reservoir I2I is provided to hold a supply of the tape necessary for recording the several digits of the designation.

In response to each opening of the subscribers line circuit during the first series of impulses transmitted by the subscribers dial I22 impulse relay I09 releases and closes a circuit from ground through its back contact, closed contacts of relay II6, winding of slow-release relay I23, through the winding of the magnetizing element I04 to the negative pole of battery I24. Each energization of the element I04 produces a magnetized area in the moving tape I02, there being as many of these magnetized areas as there are impulses in the series. These magnetized areas are permanent and remain in the tape until they have served their purpose and are erased magnetically as will be explained more fully hereinafter. Relay I23 operates on the first impulse and remains energized throughout the series. This relay closes a circuit from ground through its front contacts, brush I25, conductor I21 through the winding of the stepping magnet I26 to battery. Magnet I20 energizes preparatory to advancing the brushes of switch 5-3 to their second position terminals. In the interval between the last impulse of the first series and the beginning of the second impulse series relay I23 releases and magnet I26 deenergizes and steps the brushes of switch 8-3 to position 2. The tape I02 continues to advance so that a space is introduced between the recording of the first digit and the recording of the next digit.

When the next series of impulses are received, relay I23 reoperates to energize the magnet I26, and the recording element I04 is successively energized to magnetize the moving tape a number of times corresponding to the number of impulses in the second series. This procedure continues for the remaining digits of the designation. Assuming the designation has four digital places, the magnet I26 steps the switch S-3 out of position 4 and into position 5 following the receipt and recording of the last digit. As the switch 8-3 passes out of position 4 the circuit of the clutch magnet I I9 is opened, and the magnetic tape I02 comes to rest.

When the sender is ready to operate the selective switches, an impulse circuit is established from battery and ground through the impulse relay (not shown) in the selector switch S, over the front contacts of operated relay I28, through the brushes I29 and I30 of switch S-Z thence over conductors I3I and I32 through the winding of slow-release relay I33 and the closed contacts of relay I3 4. Relay I33 operates but does not perform any function at this time. Having prepared the impulse circuit, thesender causes the operation of stepping magnet I26 by momentarily applying ground potential net I26 operates and releases, and the switch to conductor I35. Magby the pole-pieces MI and I62. Therefore, each magnetized area of the tape passing through the gap I38 sets up a magnetic field which attracts the flexible magnetic springs #39 and I40 into contact engagement with each other. A device Each time the springs I 39 and I i-ii engage each other a circuit is completed from battery through the winding of impulse relay I33, winding of slow-release rela I 43, brush I :33 in position 5, conductor I45, contacts Ito and I39, conductor I66, brush I47, resistance I48 to ground. Relay I35 operates in response to each of these impulses and opens the impulse circuit extending to the selector switch S. Relay I53 operates in the circuit traced and closes a circuit for the stepping magnet I26. Relay I33, being slow to release, holds its armature attracted throughout the impulse series. Relay I33, being slow, also retains its armature during the intervals between the impulses of each series. The selector S responds to these impulses and advances to the desired level of contacts and then seizes an idle trunk in the level extending to the succeeding selector 'SI.

,At the end of the first outgoing impulse series the non-magnetized portion of the tape I02 passes through the gap I38 and slow-release relay Il3 retracts its armature to open the circuit of magnet I 23. Magnet I26 releases, and the brushes of switch S 3 advance to the seventh position.

The tape IGZ continues to move, and presently the magnetized areas representing the second series of impulses pass through the air-gap I38. As above described, these magnetized areas cause the successive closures of the contacts I 39 and I43 C. At the end of the second series the magnet I26 steps the switch 8-3 to position 8. In like manner the last two series of impulses are transmitted to connector switch C, and the connection is established to the called subscribers line IBI.

When the last series of. impulses has been transmitted from the tape I 32, the switch S3 advances to position I0, and the record on the tape is erased to prepare it for the next use. To this end the clutch magnet H9 is maintained in an energized condition over a circuit extending through the brush I36 in position .Ii]

magnetization produced by recording unit I34. Thereafter the tape passes through the unit I62 which is energized in the opposite direction by a somewhat weaker source I53, thus neutralizing the entire tape. The units I 53 and I '62 are energized in circuits traceable,

respectively, from the negative pole of battery I83 and the positive pole of battery I50 through the winding of units I 38 and I52, brushes I64 and I'l, through the resistances I 65 and I48 to ground.

At the proper time the control relay I39 is released, and a ground potential is momentarily applied to conductor I35 to restore the switch 8-3 to its normal position. All relays in the sender are released, and the connection between established connection is released in the wellknown manner.

In the alternate sender shown in Fig. 2 the conductors 28 i, 235, 2533 and 237, corresponding respectively to conductors H3, IM, ISI and I32, also appear in the contact banks of a sender selector switch, such as the switch 8-2. a call is nade and the sender sender selector switch, an impulse circuit is completed from battery through the winding of impulse relay 258, thence over conductor 204 through the sender selector and over the sub scribers line, returning through the sender selector and over conductor 2:75 through reactance coil 269 to ground. Relay 2% closes an obvious operating circuit for slow-release relay m. Relay ZIS closes a circuit from ground through resistance 2, contacts of relay Z'IS, brush 2I2 of sequence switch S-Q, conductor 2I3, winding 25d clutches the drive shaft 255 of the first recorder 2% to the common shaft 2I6, which is driven by the motor 2I1, to start the magnetic tape 2I8.

tape .2 I8 comes to rest, having recorded thereon the first digit of the wanted designation.

With the switch S3 in position 4- leases successively and closes a circuit from ground through its armature and back contact, front contact of relay 2l0, winding of relay 219, brush 220, conductor 220 through the winding of recording unit 221 to the negative pole of battery. The second series of impulses are recorded on the moving tape 225, following which the relay 259 releases and again the magnet 222 deenergizes to advance the brushes H2 and 220 into position 3. As the switch S4 moves out of position 2 magnet 224 becomes deenergized, and the tape 225 comes to rest.

In position 3 of the switch 8-4 the clutch magnet 228 is energized to start the recording tape 229, and the impulse circuit from relay 200 is extended over conductor 230 to the recording unit 23l. After the third series of impulses has been recorded on tape 229 the switch S-4 advances to the fourth position, the tape 229 comes to rest, and the clutch magnet 232 is energized to start the tape 233. The final series of impulses are now received and the impulse circuit from relay 208 extends over conductor 234 to the recording unit 235. These impulses are recorded on the tape 233, whereupon the switch S--4 advances into position and the tape 233 comes to rest.

At the proper time in the sequence of operations the relay 236 is operated to close the impulse circuit over conductors 206 and 201 to the first selector switch S, and relay 231 is operated to close a circuit from ground through resistance 238, contacts of said relay, brush 239 of switch S5, standing in position I, thence over conductors 240 and H3 through the winding of clutch magnet 2l4 to battery. The tape 2? resumes its movement, and the magnetized areas thereof pass through the air-gap 24! formed by the magnetic members 242 and 243. Each time a magnetized area passes through the gap 24! the magnetic contacts 244 and 245 move into engagement with each other, and a circuit is completed from battery through the winding of relay 246, brush 241, through the contacts 244 and 245, brush 248 and resistance 249 to ground Each time relay 246 operates it opens its contacts to transmit an impulse to the selector S. Relay 240 also closes an obvious circuit for slowrelease relay 250, and the latter relay closes an energizing circuit for the stepping magnet 25i. At the end of the impulse series, when the last magnetized area has passed through the air-gap 24!, relay 250 releases and opens the circuit of magnet 25L Thereupon the magnet 25! advances the brushes of switch 2, disconnecting the recorder 200 and associating the recorder 201 with the outgoing impulse circuit. The clutch magnet 224 is now energized in an obvious circuit, and the magnetic contacts 252 and 253 are included in circuit with the impulse relay 246. In the manner already described the second series of impulses are transmitted to the selector switch S--l following which the switch S5 advances to position 3 to disconnect the recorder 20! and to connect the recorder 202 with the outgoing impulse circuit. In like manner the last two series of impulses are transmitted successively from the recorders 202 and 203 to operate the connector switch C.

At some convenient time after the last series of impulses have been transmitted from the recorder 203 the sender advances the sequence switch S--5 to some subsequent position such as position 8. In this position a circuit is closed from ground through the resistance 238, con- S--5 into position i;

tacts of relay 231, brush 239 through the winding of relay 262 to battery. Relay 262 closes obvious circuits through the windings of clutch magnets 214, 224, 228 and 232. While the respective magnetic tapes are being driven by the shaft 216 a circuit is closed for the erasing units 254, 255, 256 and 251. This circuit may be traced from the source of alternating current 263 through the resistance 258, brush 259, conductor 260 and thence in parallel through the windings of said erasing units to ground. The frequency of source 263 is sufficiently high to neutralize the magnetized areas of the respective tapes, thus restoring them to their normal condition ready for the next use.

After the other necessary functions have been completed by the sender it advances the switches S-4 and S-5 to their normal positions and releases.

In the alternative reproducing unit shown in Fig. 3 the gap between the magnetic members 30! and 302 is just wide enough to permit the free passage of the tape 303. This narrow gap serves to increase the efficiency of the magnetic circuit. Since, however, the tape touches the members 30I and 302, these members are separated from the magnetic contacts 304 and 305 by thin insulating pieces 306 and 301. If desirable the members 30l and 302 may engage contacts 304 and 305, in which case the tape 303 would need to be insulated from said members.

In Fig. 4 the magnetic contact springs 40! and 402 project from the same end of the glass tube 403, and the tape 404 passes through the gap formed by these springs as shown.

What is claimed is:

1. In a telephone system, a central office, telephone lines terminating therein, automatic switches, means for sending series of impulses over a calling line representing the telephone designation of a wanted line, a magnetizable medium in said central ofiice, means responsive to said impulses for establishing a variable number of permanent magnetizations in said medium to record said telephone designation, and impulse generating contacts of magnetic material controlled by said medium in accordance with the record thereon for selectively operating said automatic switches to extend the calling line toward the called line.

2. In a telephone system, a central ofiice, telephone l'nes terminating therein, automatic switches, means for sending series of impulses over a calling line representing the telephone designation of a wanted line, a movable magnetic tape, recording means responsive to said impulses for magnetizing said tape to store said impulse series, magnetic reproducing means including impulse contacts of magnetic material coacting with the magnetized tape to reproduce said impulse series, automatic switches responsive to said reproduced impulses for selectively extending the calling line toward the called line, and means for erasing the magnetizations on said tape.

3. In a telephone system, a central office, telephone lines terminating therein, automatic switches, means for sending a plurality of series of impulses representing the successive digits of a telephone designation, a magnetizable tape at the central oflice, a recording device responsive to said impulse series for magnetizing said tape to record the designation thereon, means for directing each series of impulses to said recording device, a reproducing device including impulse contacts of magnetic material responsive to the magnetized tape to reproduce the recorded series of impulses, and an impulse circuit for delivering the reproduced impulses to said switches.

4. In a telephone system, a central office, telephone lines terminating therein, automatic switches, a common sender mechanism for controlling said switches, said sender mechanism including a recording medium, means for sending designation impulses over a calling line to the central ofiice, means responsive to said impulses for setting up in said medium areas of permanent magnetism to record the telephone designation, impulse generating contacts magnetically responsive to the areas of magnetism in said medium for reproducing the recorded impulses, and means said reproduced impulses to control operation of said switches to establish a connection from the calling line to a called line.

5. In a telephone system, a telephone line, means for sending impulses over said line representing a telephone designation, a magnetic medium, means responsive to said impulses for medium to produce flux changes in said magnetic circuit, and selective means controlled by the impulses produced by said impulse contacts.

6. In a telephone system, a telephone line, means for sending pulses over said line representing a telephone designation, a magnetic tape, means responsive to said impulses for variably magnetizing said tape to record said designation thereon, magnetic means for reproducing said impulses having a plurality of air-(gaps therein, impulse generating contacts of magnetic material located in one of said air-gaps and responsive to flux changes in said magnetic circuit, means for causing said magnetized tape to produce flux changes in said magnetic circuit by passing it through another of said air-gaps, and selective means controlled by the impulses produced by said impulse contacts.

through the other of said air-gaps to produce flux changes in said magnetic circuit and in said first air-gap, and selective means controlled by the impulses produced by said impulse contacts. impulse mechanism gap to produce flux changes in said magnetic circuit.

RICHARD J. TILLMAN. 

